In general, with respect to the device drawing a stainless round bar made of a soft material, it is important to fix forming rolls to prevent them from moving because of large force exerted to the forming rolls. In order to form round bars having a relatively large diameter into rectangular or hexagonal bars having a smaller diameter, a plurality of forming rolls are arranged in series to gradually reduce the diameter thereof during the drawing, which minimizes any forming defect which may caused by a burr in a corner occurring during the forming. Here, it is necessary to change a passage hole between forming rolls to form round bars with different diameters. Whenever it is necessary to form round bars with different diameters, the adjustment of an interval of the passage hole involves dissembling and reassembling of a mold frame and the forming rolls to adjust the passage hole, or replacing with a mold frame with a passage hole meeting a size requirement. Thus, a lot of time consumes to set the round bar forming device upon forming round bars of different sizes. Also, there may be a breakage of a bolt coupling the mold frame and forming rolls and a mold frame to which a plurality of forming rolls are coupled should be prepared to prevent the breakage.
In addition, in the case of forming a bar having a polygonal cross-section, there may be a problem of incomplete forming at the corner of the polygon because of a step occurring between a forming roll and an adjacent forming roll. To resolve this issue, Korea Patent No. 10-1254919 discloses a device for forming a round bar including a spaced bracket and roller, in which a feeding device is provided in a frame, a clamp is provided in the other frame, and a forming device is provided at the end portion of the other frame. Also, the device further includes four forming rolls having an inner rim, an outer rim producing direct friction with the round bar to process the round bar, rolling bodies deposed between the inner rim and the outer rim for the rotation of the outer rim, and a rolling body cover to fix the rolling bodies. The device also includes a bracket where two forming rolls are coupled and a second bracket where the other two forming rolls are coupled, while being spaced apart from the first bracket to prevent the incomplete forming occurring at an edge of the round bar. However, it is problematic in that when the round bar is first formed by a forming roll and then second formed by a forming roll that is spaced apart by a predetermined distance, the dimension of the surface formed during the first forming may be diminished due to force generated during the second forming, which substantially decreases the size accuracy.